Many existing microfluidic devices are configured to transmit a fluid sample from one location within the microfluidic device, e.g., a common source, to one or more alternative locations within the microfluidic device, e.g., one or more sample chambers. In particular embodiments in which microfluidic devices are configured to transmit a fluid sample from one location within the microfluidic device to a single alternative location within the microfluidic device, existing microfluidic devices may use dead-end filling, in which the fluid sample is transferred into a closed system against an internal pressure of the closed system. Dead-end filling enables precise filling of the single location of the microfluidic device such that overflow of the fluid sample, and thus waste of fluid sample, is minimized. This precision provided by dead-end filling is particularly important in embodiments in which the fluid sample comprises expensive components.
In alternative embodiments in which microfluidic devices are configured to transmit a fluid sample from one location within the microfluidic device to multiple alternative locations within the microfluidic device, this transfer of the fluid sample is oftentimes performed asynchronously such that one or more of the locations completes filling at different times. Asynchronous completion of filling is problematic in embodiments in which the microfluidic device is used to perform assays, because the reliability of the assay results depends upon the uniformity of the variables that affect the results, such as reaction timing. Furthermore, asynchronous filling of the multiple locations of the microfluidic device may result in imprecise filling of one or more of the multiple locations of microfluidic device such that overflow of the fluid sample, and thus waste of fluid sample, occurs. Not only is this particularly undesirable in embodiments in which components of the fluid sample are expensive, but in embodiments in which the microfluidic device is used to perform assays, imprecise filling can increase the likelihood of heterogeneity of the fluid sample across the multiple locations, thereby further tarnishing the reliability of the assay results. In addition to these shortcomings of the existing microfluidic devices described above, many existing microfluidic devices also do not include built-in features to facilitate actuation of assays.
The novel devices described herein include microfluidic devices that are configured to control transmission of a fluid sample from a common fluid source to multiple sample chambers using dead-end filling, such that the multiple sample chambers are filled concurrently. The devices described herein enable precise filling of the multiple sample chambers such that overflow of the fluid sample, and thus waste of the fluid sample is minimized. Furthermore, concurrent filling of the multiple sample chambers, as enabled by the devices described herein, increases the likelihood of homogeneity of the fluid sample across the multiple sample chambers, and improves the uniformity of reaction timnng across the multiple sample chambers, thereby improving the reliability of assay results generated by the microfluidic device.
In certain embodiments, the novel devices described herein also include features to facilitate actuation of assays. For instance, in certain embodiments, one or more of the sample chambers of the novel devices described herein comprise a double tapered chamber that minimizes the trapping of bubbles within the sample chamber during filling with the fluid sample. Minimizing bubble trapping is advantageous during assay actuation because in some embodiments, bubbles interfere with the results of the assay.